The present invention relates to a plane-surfaced waved out-diffusion triangular beam-typed resonant board, particularly a low-costed and easy to produce resonant board having a strength to withstand vibration without deformation.
A resonant board is a component for changing a tone by changing strength of sound, and hence a good speaker requires a sufficient resonant board strength to withstand vibration without deformation.
Conventionally the resonant board for a speaker has a voice coil adhered to the middle. Vibration can deform the voice coil. Moreover, for a low frequency speaker, the larger the diameter, the thicker the speaker. Though there has been a so-called "cellular type plane-surfaced speaker" in the market, it was developed in Japan and the U.S. for another purpose. It is a light and high pressure resistant plane surfaced board and is not particularly designed for use as speaker. Its production is difficult, and its production cost is very high. Moreover, a conical structure has to be adhered to the cellular type plane-surfaced board for connection to a coil, which means that it is not suitable for making a thin-type low frequency speaker because of its height.